Individually hermetically sealed cathode-ray tubes connected by fiber optics array

ABSTRACT

An improved scan-conversion device is provided in the form of a combination of two separate cathode-ray tube sections utilizing a common faceplate portion therebetween. A method of fabrication embodies peripherally sealing an envelope funnel to a first surface of the common faceplate, whereupon a cathodoluminescent screen is formed. Upon positioning and sealing an electron gun in the funnel portion of the first envelope, the envelope is evacuated, sealed and processed to provide a display-forming section. A target electrode is then formed on the outer surface of the common faceplate, and a second envelope funnel, having an electron gun positioned and sealed therein, is peripherally bonded thereto; whereupon the second envelope is evacuated, sealed and processed to provide a display-reading section oriented to directly cooperate with the display-forming section.

United States Patent Harry E. Smithgall;

Elmer 0. Stone, both of Seneca Falls, N .Y. 886,109

Dec. 18, 1969 Nov. 30, 1971 GTE Sylvania Incorporated [72] Inventors[21] Appl No. [22] Filed [45] Patented [73] Assignee [54] INDIVIDUALLYHERMETICALLY SEALED CATHODE-RAY TUBES CONNECTED BY FIBER LP, 65 US, 68US [56] References Cited UNITED STATES PATENTS 3,182,223 5/1965 McNaney315/10 2,922,070 1/1960 Seevers 315/9 Primary Examiner- Robert SegalAttorneys-Norman .1. OMalley, Donald R. Castle and Frederick H. RinnABSTRACT: An improved scan-conversion device is provided in the form ofa combination of two separate cathoderay tube sections utilizing acommon faceplate portion therebetween. A method of fabrication embodiesperipherally sealing an envelope funnel to a first surface of the commonfaceplate, whereupon a cathodoluminescent screen is formed. Uponpositioning and sealing an electron gun in the funnel portion of thefirst envelope, the envelope is evacuated, sealed and processed toprovide a display-forming section. A target electrode is then formed onthe outer surface of the common faceplate, and a second envelope funnel,having an electron gun positioned and sealed therein, is peripherallybonded thereto; whereupon the second envelope is evacuated, sealed andprocessed to provide a display-reading section oriented to directlycooperate with the display-forming section.

PATENTEDNU 0 3.824.442

INVENTORS HARRY E. SMITHGALL & EL MER O. STONE y" ATTORNEY INDIVIDUALLYHERMETICALLY SEALED CATHODE- RAY TUBES CONNECTED BY FIBER OPTICS ARRAYBACKGROUND OF THE INVENTION This invention relates to a cathode-ray tubecombination and more particularly to an integrated scan-conversiondevice and method of fabrication.

Cathode-ray tube structural combinations are conventionally used asscan-conversion devices wherein one portion of the device serves toread-in a certain type of information, and another portion functions toa translation of the information in another desired form. Such devicesare employed where display information is continuously transformed fromone scanning rate or time base to another ofa difiering value. Forinstance, by employing suitable components and appropriate deflectionsignals. the form of input scan is readily converted to a different formof output scan, i.e. a PP]. radar display to a horizontal scanrectangular presentation. Scanconversion devices also make possible achange in the rate of scan frequency during the respective read-in andreadout operations. One common type of scan-conversion device is in theform of a single unitized envelope having a series of fine mesh metallicscreens positioned in a common vacuum environment in a manner tofunction as respective writing, storage, collecting, and readingelements. Appropriate electron guns, oriented at either end of the tube,serve to read-in and read out the desired information. Such tubes arecomplex structures embodying a combination of accurate mechanical andelectrical tolerance requirements which contribute to the cost anddifficulty of fabrication. Since the several structures are contained ina common envelope, one defect occurring during the final stages ofmanufacturing can ruin the complete structure, thereby greatlyincreasing the costs of fabrication. Attempts have been made tofabricate double-ended cathoderay tubes having a common faceplate,whereof difficulties in glass sealing and screen deterioration resultantof glass sealing temperatures have been encountered.

OBJECTS AND SUMMARY OF THE INVENTION It is an object of the invention toreduce the aforementioned disadvantages and to provide an improvedscan-conversion device embodying two individual hermetically sealed andevacuated cathode-ray tube enveloped structures having a commonfaceplate therebetween.

Another object is to provide a method of fabricating a scanconversiondevice embodying two separate and distinct cathode-ray tube structureshaving a common faceplate therebetween.

A further object is to provide a scan-conversion device that can beexpeditiously and economically manufactured.

The foregoing objects are achieved in one aspect of the invention by theprovision ofa scan-conversion device embodying a combination of twoseparate cathode-ray tube sections utilizing a common faceplate portion.The individual cathoderay tube sections provide display-forming anddisplay-reading sections respectively. A method of fabrication isprovided wherein a first envelope funnel is peripherally joined to afirst surface of the common faceplate portion to provide a firstenvelope portion. A cathodoluminescent screen is formed on the faceplateof the first envelope portion. Upon positioning and sealing an electrongun in the neck portion of the first envelope, sequential evacuation,sealing and processing provides a completed first display-formingsection. A target electrode or screen is formed on the second orexterior surface of the common faceplate, whereupon a second envelopefunnel, having an electron gun positioned and sealed therein, isperipherally joined to the faceplate to provide a second envelope means.The second envelope is then sequential evacuated, sealed, and processedto provide a completed second display-reading section which is orientedto functionally cooperate with the aforementioned display-formingsection. Thus, there is provided a cathode-ray tube scan-conversiondevice employing separate evacuated sections wherein opposite surfacesof the common faceplate are scanned by different electron beamsrespectively.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view of thescan-conversion device illustrating the aspects of one embodiment of theinvention; and

FIG. 2 is an enlarged fragmentary plan view of the common faceplateregion of the device illustrating aspects of a second embodiment of theinvention.

DESCRIPTION OF THE PREFERRED EMBODIMENT For a better understanding ofthe present invention, together with other and further objects,advantages and capabilities thereof, reference is made to the followingspecification and appended claims in connection with the aforedescribeddrawing.

With reference to the drawing, there is shown in FIG. I a plan view of ascan-conversion device 11, having an axis 12 and incorporating incombination, a cathode-ray tube displayforming section 13 and acooperating cathode-ray tube display-reading section 15. In the deviceembodiment shown, the display-reading section 15 is, for example, acathode-ray tube structure in the form of a photoconductive camera orpickup tube such as a Vidicon camera tube. However, it is not intendedthat the display-reading section be limited to a camera tube, as othercathode-ray tube structures such as a display storage medium canlikewise be employed in keeping with the intended scope of theinvention. Likewise, the display-forming section 13 is not to be limitedto a conventional monochrome screen, but is intended to also includeplural phosphor screens, exhibiting multiple decay characteristics,responsive to excitation by electron beams of different velocities.

A substantially planar faceplate portion 17, as illustrated in FIGS. 1and 2, is common to both display sections 13 and 15, and is of athickness 11" to minimize capacitive coupling between the first 19 andsecond surface 21 thereof. The com mon faceplate 17 is substantiallytransparent being of a material such as a fiber optics array, whereinmultitudinous glass rods 23 are arranged in an orderly manner totransmit high resolution display imagery between the respectivefaceplate surfaces 19 and 21. It has been found that a fiber opticsfaceplate 17 having a thickness a," for example within the range of 0.5to L0 inch, is beneficial in minimizing crosstalk between the surfaces19 and 21.

The envelope of the display-forming section 13 has a first envelopefunnel portion 25 which is hermetically joined to the peripheral regionof the first surface 19 of the faceplate by a glass formed frit seal 26to provide a first envelope means 27. This frit seal is accomplished,for example, within a temperature range of 400 to 450 C., and does notaffect the structure of the fiber optics array.

The definition of funnel," in this instance, is intended to include botha tubular portion alone, or a tubular or conical portion with acontiguous smaller diametered neck portion attached thereto.

A cathodoluminescent display screen 29, having therein at least oneelectron responsive phosphor, is disposed on the first faceplate surface19 to provide the screen for the displayforming section 13.

The inner surface of the first envelope funnel 25 has an electricalconductive coating 30 discretely applied thereto in a manner to extendsubstantially from the region of the screen 29 to an electron gun orbeam generating means 31 positioned in the envelope funnel 25. Theelectron gun 31 has a plurality of connective leads 33, two of which areshown, extending exteriorly of the tube through a stem closure portion35. Another electrical connective means 37 extends exteriorly throughthe envelope 27 from the region of the screen to provide means forsupplying a final anode voltage to the displayforming sectiin 13. A thinmetallic coating 39, such as aluminum, is suitably disposed over thesurface of the screen 29 and a portion of the adjacent conductivecoating 30. This metallic coating 39 enhances the display imagery of thescreen projected through the faceplate 17 and insures electricalconnection of the screen 29 and the conductive coating 30 with theelectrical connective means 37.

The cathoderay tube display-reading section is formed of a secondenvelope funnel portion 41 which is hermetically sealed to theperipheral region of the second surface 21 by a glass-metal seal 42,such as indium, to provide a second envelope means 43.

A photoconductive screen or target electrode 45 is disposed on thesecond surface 21 of the common faceplate 17. This target electrode 45comprises a layer of photoconductive material 47 such as antimonytrisulfide deposited over a thin substantially transparent electricalconductive film 49 comprised of at least one metallic material selectedfrom the group consisting of tin oxide, gold, and chromium. Theaforementioned glass-metal seal 42 provides internal to externalelectrical connective means for the target electrode 45. Attached to theglass-metal seal 42 is a metallic ring or band 51 of a material such asstainless steel, which provides external terminal means for the targetelectrode 45.

Positioned adjacent the target electrode 45 is a conventional planarmesh grid 53 which is supported by an insulative ring 55 mounted on theforward open end of the G-3 electrode 57 of the electron gun 59. Aplurality of external con nective leads 61, two of which are shown,extend from the electron gun 59 through the stem closure portion 61.

Focusing and deflection systems 63 and 65 are auxiliary operationalmeans oriented relative to the exterior of the respectivedisplay-forming section 13 and the display-reading section 15. Althoughmagnetic systems are shown in FIG. 1, electrostatic systems or anycombination of the two can be equally employed for either or bothdisplay sections.

A second embodiment of the scan conversion device 11 is illustrated inFIG. 2, wherein the electrical connection from the region of thecathodoluminescent display screen 29 to the exterior of the firstenvelope means 27 is in the form of a plurality of conductive leads 67embedded in and extending through the frit seal jointure 26. Theseconductive leads 67 are of a metallic composition, such anickel-chromium-iron alloy, having expansion characteristicssubstantially matching those of the material of the glass frit seal 26.An example of such a material is No. 4 Alloy as manufactured by SylvaniaElectric Products lnc., New York, NY. The conductive leads 67 extendexteriorly of the seal 26 and are of a sufficient length to facilitate abonded jointure 69 with a conductive terminal ring, or band 71. Exteriorsupport for the terminal band 71 is provided by a supportive adhesivematerial 73 exhibiting sufficient resilience to accommodate thedifferential of expansion characteristics of the contiguous associatedmaterials. An example of a suitable supportive material 73 is aroom-temperature-setting silicone rubber adhesive/sealant material suchas Silastic RTV silicone rubber as manufactured by the Dow CorningCorporation, Midland, Mich.

One method for fabricating a scan-conversion device of an aforedescribedtype comprises a definite sequence of related steps. It has been foundexpedient to first construct the display-forming section 13 wherein thefirst envelope funnel portion 25 is joined to the peripheral region ofthe first surface 19 of the faceplate 21 by a glass frit seal 26 toprovide a first envelope means 27. Next, a cathodolurninescent displayscreen 29, of at least one electron responsive phosphor, is formed byconventional means on the first faceplate surface 19. An electricalconductive coating 30, of a material such as colloidal graphited water,for example Aquadag, is applied to a discrete area of the inner surfaceof the first envelope means 27 in a manner to extend from the region ofthe screen 29 to the location of the electron gun 31. it is preferableto aluminize the region of the screen 19 which is accomplished in aconventional manner by applying a lacquer substrate, not shown, uponwhich a thin film of aluminum 39 is vaporized. An electrical connectionfrom the electrical conductive coating 30 in the region of the screen 29is made, for example, by electrical connective means 37 which traversesthe wall of the first envelope means 27. The screened and coated firstenvelope is then heated, for example, at approximately 400 C. for aboutone-half hour, to remove volatile substances from the screen andcoatings contained within the tube envelope. The electron gun 31,supported by the stem closure portion 35, is then positioned within thefirst envelope means 27, whereupon the stem closure 35 is peripherallyand hermetically joined to the envelope as by seal 74. The firstenvelope means 27 is then evacuated or exhausted through a suitableopening therein, for example, a tubulation in the stem closure portion35 which is subsequently closed by seal 75. Conventional processing isthence completed to provide the first display-forming section 13.

A substantially transparent electrically conductive film 49 is appliedto the second surface 21 of the faceplate 17 as by, for example, thevaporization of a thin film of at least one metal, selected from thegroup consisting of gold and chromium. Upon this conductive film 49, aphotoconductive coating 47, of a material such as antimony trisulfide,is applied by vapor depositing several thin superjacent layers toprovide the desired photoconductive deposition. The transparentelectrically conductive film 49 and the overlaid photoconductive coating47 provide the target electrode 45 for the displayreading section 15under construction.

An indium sealing ring, interiorly adhered to a metallic backing band51, is positioned to effect cold-sealing of the second envelope funnelportion 41 to the peripheral region of the second surface 21 of saidfaceplate portion 17 containing the target electrode 45. In thisinstance, the second envelope means 43 has an electron gun 59 priorlypositioned and sealed therein; the electron gun being supported by stemclosure por tion 61. The second envelope funnel 41 with the electron gun59 therein is carefully pressured in an axial manner against the indiumsealing ring positioned on the faceplate 17, by means not shown, wherebythe indium ring is plastically deformed to provide the glass'metal seal42. No heat is required for this type of seal which makes it appropriatefor this jointure as the adjacent antimony trisulfide would notwithstand the temperature normally required to effect a glass frit typeof seal. Since the indium is electrically conductive, the seal 42provides an electrical connection from the target electrode 45 to theexterior of the second envelope 43. The metallic backing band 51provides the exterior connective element for the target electrode 45.

The second envelope 43 is then evacuated or exhausted through a suitableopening therein, such as for example, a tubulation in the stem closureportion 61 which is subsequently closed by seal 77. Althoughconventional processing is employed to provide the seconddisplay-reading section 15 of the scan-conversion device 11, care isexercised to protect the indium seal from temperatures exceeding l20 C.

Another embodiment for consummating the electrical connection from theregion of the screen 29 to the exterior of the first envelope portion 25is accomplished by inserting and embedding a plurality of electricallyconductive leads 67 in the frit sealjointure 26 at the time thatjointure is made.

It has been found that by another method of fabrication, thesubstantially transparent electrically conductive film 49, thatcomprises part of the target electrode 45 of the display-reading section15, is applied as a first step. By this technique, the faceplate portion17 is discretely heated at a differential of about 2 C. per minute to atemperature of approximately 600 C., whereupon the second surface 21 ofthe faceplate has stannic chloride evenly applied thereto to provide aconductive tin oxide coating thereover. When the transparent conductivefilm 49 is applied at this stage of fabrication, care must be exercisedto protect this film during the subsequent fabrication of thedisplay-forming section 13.

Thus, there is provided an improved scan-conversion device embodying twoindividual hermetically sealed and evacuated cathode-ray tube envelopedstructures having a common faceplate therebetween. The device exhibitshigh sensitivity since light from the phosphor screen of thedisplay-forming section is coupled directly to the target electrode ofthe display-reading section In addition, the combination structure ofthe device facilitates economical and expeditious fabrication.

While there has been shown and described what are at present consideredthe preferred embodiments of the invention it will be obvious to thoseskilled in the art that various changes and modifications may be madetherein without departing from the scope of the invention as defined bythe ap pended claims.

What is claimed is:

1. A scan-conversion device having two individual hermetically sealedand evacuated envelope sections providing a first cathode-ray tubedisplay forming section and a second cathode-ray tube display readingsection each having individual funnel portions and separate electronbeam generating means therein, said device comprising:

a substantially planar faceplate portion in the form of a fiber opticsarray common to both of said envelope sections and having a thickness tominimize capacitive coupling therebetween, said first and secondenvelope funnel sections being joined peripherally to respective firstand second surfaces of said faceplate; the jointure between saidfaceplate first surface and said first envelope section being a glassformed frit seal, the jointure between said faceplate second surface andsaid second envelope section being a glass-metal seal capable of beingconsummated at a temperature lower than that required to make a glassformed frit seal;

a cathodoluminescent display screen formed of at least one electronresponsive phosphor on said first faceplate surface to provide thescreen for said display forming section;

an electrical conductive coating disposed on the inner surface of saidfirst envelope funnel portion in a manner to extend substantially fromthe electron beam generating means therein to the region of saidcathodoluminescent screen;

an electrical connection extending from the region of saidcathodoluminescent screen to the exterior of said first envelope; saidelectrical connection being in the form of a plurality of conductiveleads embedded in and extending through said frit seal jointure;

a photoconductive screen formed on said second surface of said faceplateportion to provide a target electrode for said display reading section,said photoconductive screen comprising a layer of photoconductivematerial deposited over a substantially transparent electricalconductive film formed on said second faceplate surface; and

electrical connective means from said transparent electrical conductivefilm through said glass-metal seal to the exterior thereof.

2 A scan-conversion device according to claim 1 wherein said commonfaceplate portion has a thickness exceeding 0.5 inch.

3. A scan-conversion device according to claim 1 wherein saidsubstantially transparent electrically conductive film on said secondfaceplate surface is in the form of at least one metallic materialselected from the group consisting of tin oxide, gold. and chromiumr 3 33 4 UNHED STATES PATENT OFFICE CERTIFICATE CF CORRECTION Patent no.3,624,442 Dated November 30, 1971 Inventofls) Harry E. Smithgall andElmer 0. Stone It is certified that error appears in theabove-identified patent and that said Letters Patent are herebycorrected as shown below:

Col. l, line 11 in the Specification "to a translation" should read "toread-out a translation" Signed and sealed this 23rd day of May 1972.

(SEAL) attest.

EWJARD lI.FLETClER,-IR. ROBERT GOTTSCHALK Attesting Officer Commissionerof Patents

1. A scan-conversion device having two individual hermetically sealedand evacuated envelope sections providing a first cathoderay tubedisplay forming section and a second cathode-ray tube display readingsection each having individual funnel portions and separate electronbeam generating means therein, said device comprising: a substantiallyplanar faceplate portion in the form of a fiber optics array common toboth of said envelope sections and having a thickness to minimizecapacitive coupling therebetween, said first and second envelope funnelsections being joined peripherally to respective first and secondsurfaces of said faceplate; the jointure between said faceplate firstsurface and said first envelope section being a glass formed frit seal,the jointure between said faceplate second surface and said secondenvelope section being a glass-metal seal capable of being consummatedat a temperature lower than that required to make a glass formed fritseal; a cathodoluminescent display screen formed of at least oneelectron responsive phosphor on said first faceplate surface to pRovidethe screen for said display forming section; an electrical conductivecoating disposed on the inner surface of said first envelope funnelportion in a manner to extend substantially from the electron beamgenerating means therein to the region of said cathodoluminescentscreen; an electrical connection extending from the region of saidcathodoluminescent screen to the exterior of said first envelope; saidelectrical connection being in the form of a plurality of conductiveleads embedded in and extending through said frit seal jointure; aphotoconductive screen formed on said second surface of said faceplateportion to provide a target electrode for said display reading section,said photoconductive screen comprising a layer of photoconductivematerial deposited over a substantially transparent electricalconductive film formed on said second faceplate surface; and electricalconnective means from said transparent electrical conductive filmthrough said glass-metal seal to the exterior thereof.
 2. Ascan-conversion device according to claim 1 wherein said commonfaceplate portion has a thickness exceeding 0.5 inch.
 3. Ascan-conversion device according to claim 1 wherein said substantiallytransparent electrically conductive film on said second faceplatesurface is in the form of at least one metallic material selected fromthe group consisting of tin oxide, gold, and chromium.